diff --git a/source/client/src/clientImpl.c b/source/client/src/clientImpl.c
index 7838d87a203bc2d9de35fbac0c84f0204aed73b6..d3079a48d73b9140da5987bec979cc98910d40b4 100644
--- a/source/client/src/clientImpl.c
+++ b/source/client/src/clientImpl.c
@@ -1571,10 +1571,18 @@ static int32_t doConvertUCS4(SReqResultInfo* pResultInfo, int32_t numOfRows, int
   return TSDB_CODE_SUCCESS;
 }
 
+static int32_t getVersion1BlockMetaSize(const char* p, int32_t numOfCols) {
+  int32_t cols = *(int32_t*) (p + sizeof(int32_t) * 3);
+  ASSERT(numOfCols == cols);
+
+  return sizeof(int32_t) + sizeof(int32_t) + sizeof(int32_t)*3 + sizeof(uint64_t) + numOfCols * (sizeof(int8_t) + sizeof(int32_t));
+}
+
 static int32_t estimateJsonLen(SReqResultInfo* pResultInfo, int32_t numOfCols, int32_t numOfRows) {
   char* p = (char*)pResultInfo->pData;
 
-  int32_t  len = sizeof(int32_t) + sizeof(uint64_t) + numOfCols * (sizeof(int16_t) + sizeof(int32_t));
+  // version + length + numOfRows + numOfCol + groupId + flag_segment + column_info
+  int32_t  len = getVersion1BlockMetaSize(p, numOfCols);
   int32_t* colLength = (int32_t*)(p + len);
   len += sizeof(int32_t) * numOfCols;
 
@@ -1642,7 +1650,7 @@ static int32_t doConvertJson(SReqResultInfo* pResultInfo, int32_t numOfCols, int
   char* p1 = pResultInfo->convertJson;
 
   int32_t totalLen = 0;
-  int32_t len = sizeof(int32_t) + sizeof(uint64_t) + numOfCols * (sizeof(int16_t) + sizeof(int32_t));
+  int32_t len = getVersion1BlockMetaSize(p, numOfCols);
   memcpy(p1, p, len);
 
   p += len;
diff --git a/tests/script/tsim/compute/diff2.sim b/tests/script/tsim/compute/diff2.sim
index a09bee991eeb8f6333ebd7b4331a99782877a715..5a2c3706eec8381975a3b84ee5dfdaa0964ebb65 100644
--- a/tests/script/tsim/compute/diff2.sim
+++ b/tests/script/tsim/compute/diff2.sim
@@ -78,7 +78,6 @@ endi
 sql select diff(c7) from $tb
 sql_error select diff(c8) from $tb
 sql_error select diff(c9) from $tb
-sql_error select diff(ts) from $tb
 sql select diff(c1), diff(c2) from $tb
 
 sql select 2+diff(c1) from $tb